Fair enough,
If you need the observations to equal the number of visits and you need to keep the data from each visit, you are going to need to use the reshape wide function on the master dataset before the merge. Since you said that you have 70 variables for each visit, you will now have 70 * the max number of visits variables. Depending on your version of Stata you may or may not be able to work with that many variables.
You can get help with this function using:
help reshape
Quinn Swanquist
qswanqui@utk.edu
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Claude Beaty
Sent: Tuesday, June 12, 2012 5:31 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: RE: Combining multiple observations by an ID variable
Mr. Swanquist,
It looks like the merger attempt was likely successful, though I'm sure there are some duplicates. However, your suggested code did not help to shift the data so that the total observations equal the number of ID codes instead of the number of visits. I have tried reshaping etc, but there are too many macros to reshape all of the variables. Is there another way? If I can arrange the data in this way, it is easier to compare with my previous file and find duplicate ID codes. As it stands now, it is difficult to tell if duplicate ID codes are due to successive visits or duplications created by the file merger. Thanks
Claude A. Beaty Jr., M.D.
Halsted Surgical Resident
Cardiac Surgery Research Fellow
The Johns Hopkins Hospital
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Swanquist, Quinn Thomas
Sent: Tuesday, June 12, 2012 5:16 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: Combining multiple observations by an ID variable
Do you have an identifier for visit number (if not you could use date).
Sort as follows:
sort IDcode visit
then merge many to one as follows:
merge m:1 IDcode using "usingfile"
Quinn Swanquist
qswanqui@utk.edu
-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Claude Beaty
Sent: Tuesday, June 12, 2012 5:02 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: Combining multiple observations by an ID variable
All,
I have a large dataset of observations in which individuals (~40,000 ID codes) were evaluated multiple times (5-10 visit numbers per individual) on over 70 variables. However, the data has been arranged so that each visit number is an observation, instead of each individual ID code as an observation. I need to merge this file with another file sorted by individual ID codes. How do I rearrange this data so that it is arranged by ID codes with consecutive follow up visits? Thanks
Claude A. Beaty Jr., M.D.
Halsted Surgical Resident
Cardiac Surgery Research Fellow
The Johns Hopkins Hospital
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